Nepeta cataria, commonly known as catnip, catswort, or catmint.
It is a species of the genus Nepeta in the family Lamiaceae.
Catnip is native to southern and eastern Europe, the Middle East, central Asia, and parts of China.
It is also widely naturalized in northern Europe, New Zealand, and North America.
The common name catmint can also refer to the genus as a whole.
The names catnip and catmint are derived from the intense attraction most cats have towards them.
Catnip has a history of medicinal use for a variety of ailments.
The plant has been consumed as a tea, juice, tincture, infusion or poultice, and has also been smoked.
However, its medicinal use has fallen out of favor with the development of more commonplace pharmaceutical drugs. (source)
So can guinea pigs eat catnip at all?
It is not a good plant to give your piggie and should be avoided if possible as it may hurt their stomach if digested.